The sister of Salam Mukhaibir collapses as her brother’s body arrives at a Yazidi temple near Iraq’s Mount Sinjar. The 18-year-old was killed in clashes against peshmerga forces in Khana Sour. (Alice Martins/For The Washington Post)

SINJAR, Iraq — Relatives collapsed in grief as the coffin of an 18-year-old Yazidi fighter was carried to a small temple at the base of Mount Sinjar.

Salam Mukhaibir’s death this month, along with four other Yazidi fighters, marked the latest dark turn for an Iraqi minority sect that has suffered genocide at the hands of the Islamic State.

But the men were not killed fighting the militants. They died in clashes with Kurdish peshmerga forces when long-simmering rivalries erupted.

The Islamic State overran the town of Sinjar and its surroundings 2½ years ago, executing thousands of Yazidi men, whom it considers apostates. Thousands of women who were kidnapped to be used as sex slaves and their children remain missing.

But the fierce infighting among forces ostensibly meant to be battling the militants now threatens to set back efforts to recapture more land and rebuild areas reduced to rubble.

The conflagration presents a challenge for the United States, which plays a role supporting both Kurdish factions involved — providing military assistance to them, or their affiliates, in the fight against the Islamic State. It also marks a bleak bellwether for the prospects of peace after territory is finally won back from the Islamic State. In neighboring Syria, U.S. troops have already been diverted to prevent warring between rival forces they support.

At a strategic crossroads between Syria, Turkey and Iraq, the traditional Yazidi heartland has become a flash point for Kurdish political rivalries, fueled by the wider competing interests of Turkey, Iran and the Iraqi government in Baghdad.

“We feel like a toy in the hands of the politicians,” Khalaf Bahri, a Yazidi religious sheikh, said before performing the burial rites for the young man, whose body was carried to a cemetery on the mountainside. “Yazidis are wounded and still bleeding. We still have our sisters and daughters and wives in the hands of Islamic State, but now this.”

The body of Salam Mukhaibir is carried by relatives. He was buried in a cemetery on the mountainside. (Alice Martins/For The Washington Post)

The slain Yazidi fighters belonged to the Sinjar Resistance Units, a local force affiliated with the military wing of the Kurdistan Workers’ Party, or PKK, a separatist group from neighboring Turkey. The United States has been providing arms to a coalition of forces over the border in Syria led by another PKK affiliate. Some fighters with the Yazidi group carried U.S.-made M-16 rifles. They said the firearms were captured from Islamic State militants or purchased on the black market.

On the other side of the confrontation was the Rojava Peshmerga, largely Syrian Kurds under the command of Kurdistan’s regional government, which the U.S.-led coalition is also supporting in its fight against the Islamic State. They fled to Iraq at the beginning of Syria’s civil war and have been blocked from returning home.

Both sides accuse the other of shooting first.

Kurdish President Masoud Barzani has repeatedly asked the PKK to leave Iraq. But many Yazidis credit the group with saving them when peshmerga forces charged with protecting them abandoned their posts with little fight during the Islamic State’s onslaught in 2014.

Tens of thousands of Yazidis became trapped atop Mount Sinjar as they sought refuge there. Those who did not make it ended up as Islamic State captives or were killed and thrown into one of the dozens of mass graves that surround the mountain.

The plight of those stuck on the mountain and surrounded by militants sparked the first aerial bombardment in Iraq by the U.S.-led coalition against Islamic State fighters. But it was the PKK and its Syrian affiliate that fought to open a land route to allow Yazidis to escape on foot.

Since then, the PKK has put down roots, opening schools and training Yazidi fighters. Pictures of Abdullah Ocalan, the group’s figure­head, are ubiquitous in the area. A shrine on the mountainside, illuminated at night, is dedicated to more than 200 fighters from the PKK and aligned factions who died fighting here.

To Kurdistan’s semiautonomous government in northern Iraq, Sinjar is an integral part of its territory. The Iraqi government disputes that claim. Many Yazidis consider themselves ethnically Kurdish.

After Kurdish forces recaptured the town a year and a half ago, Barzani said in a triumphant speech from the mountainside that the Kurdish flag would be the only one to fly there. Since then, his party has expanded its influence, but the PKK has stayed put.

“We are vulnerable and in a weak position, so whoever gives us a piece of bread, a house, a weapon — people will take it,” said Bahri, the Yazidi sheikh at the funeral, who is aligned with Yazidi-PKK forces. “Our leaders have sold themselves for money.”

‘We have been betrayed’

As the rival sides vie for influence, thousands of Yazidis who took up arms against the Islamic State have also joined the peshmerga.

Hayder Shesho, who heads a force of Yazidi fighters, is integrating 1,000 of them into peshmerga ranks.

Shesho said he has decided to merge his forces with the peshmerga because it was the “only open door.” He said he was arrested in 2015 in what he describes as an attempt to “pressure” him.

“Yes, we have been betrayed by them. Yes, we have been abandoned by them,” he said of the Kurdish regional government’s ruling party. “But we are Kurds.”

He said the U.S.-led coalition should “take responsibility” and unite Yazidis, calling for international forces to protect them. “No one represents the Yazidis,” he lamented.

The clashes in recent weeks have sent thousands of Yazidi families that had returned to villages fleeing once more, some back to the mountain that provided them sanctuary in 2014.

“We’re poor; we’ve been through genocide,” said Gowri Mitchka, who was putting up tents with 20 members of her extended family. “We don’t want to be a part of this. We need help.”

Farther up the road, on the winding track that leads over the mountain, someone has spray-painted words that echo the sentiments of many here: “Yazidism unites us, the parties divide us.”

Gowri Mitchka, in white, and her relatives set up a tent in Sinjar after fleeing clashes in Khana Sour. (Alice Martins/For The Washington Post)

Two days after the clashes this month, the peshmerga — riding atop bulldozers — created large earthen barriers between the two sides, and soldiers restricted traffic along the road. The other side was also building defenses.

Maj. Gen. Bahjat Taymis, a peshmerga commander, said the fighting started when Rojava Peshmerga were on a mission to cut off smuggling routes. The fighters were setting up a base on the edge of the village of Khana Sour when they were surrounded, and reinforcements that were sent in were then fired upon, he added.

The PKK said the fighting began after two of its fighters were shot dead as they tried to block the advancing peshmerga convoy. The five Yazidis died in those clashes, according to PKK and Yazidi commanders.

Shesho and PKK commanders said the decision to deploy a foreign force — the largely Syrian Rojava Peshmerga — was a deliberate provocation. Kurdistan’s government contends that it can deploy forces in its territory as it wishes.

A female member of the YBS, a PKK-affiliated Yazidi armed group, surveys the scene in Khana Sour. (Alice Martins/For The Washington Post)

Circumventing the barriers between the two sides involves navigating dirt tracks at the foot of the mountain. On the other side, Yazidi fighters set up new mortar positions. But instead of pointing at the Islamic State militants, they were angled toward peshmerga.

“First, we will try and solve this through dialogue, but if not we will fight them, because it’s the will of the people,” said Zardasht Shingali, a 30-year-old commander with the group. “They are distracting us from fighting the Islamic State.”

He said the opponents were not real peshmerga but “thugs.”

“We consider Sinjar part of Kurdistan, and we have no problem with the peshmerga,” he said. “But these people are gangsters, working on a Turkish agenda.”

Turkey considers the PKK a terrorist group and has said it will not let Sinjar become a “new Qandil,” referring to the mountain range in northern Iraq that has become a hideout for PKK forces waging attacks against the Turkish state.

Others say the Sinjar Resistance Units are also influenced by outside forces, through their close relationship with the PKK and links to the Iraqi government’s popular mobilization forces, which are dominated by Iranian-backed militias.

“We will not accept a Turkish agenda or an Iranian agenda. Turkey and Iran are trying to pull Sinjar into a regional conflict, and Sinjar will not accept it,” said Mahama Khalil, the mayor of Sinjar, who belongs to the same party as Kurdistan’s president. He added that the PKK should leave.

But for the Iraqi government, the PKK presence in Sinjar provides a counterbalance to Kurdistan’s ruling party and Yazidi fighters said Baghdad paid their wages until late last year.

Commanders with the Sinjar Resistance Units insist that they are independent and receive support only from their community. However, lines distinguishing it from the PKK are blurred, and Turkish and Iranian Kurds are among their ranks.

One 35-year-old Kurdish Iranian manning a checkpoint said he was moved from the PKK’s military wing to the Yazidi force about 15 months ago. A 17-year-old fighter with the group also said he was from Iran.

Agit Civiyan, a commander for the PKK’s military wing in Sinjar, said some fighters were integrated into the Yazidi ranks for “training and education” purposes. He said the PKK was ready to leave when no longer needed, but that the Yazidis still required protection.

While the infighting continues, little has been done to rebuild Sinjar — Kurdish officials say they cannot begin until the PKK leaves — and areas nearby are still under Islamic State control.

On the mountain, Jamil Khalaf said he was tired of all sides.

“We blame them all,” he said. “They don’t care about anyone else. Why are they fighting each other when they should be liberating our villages?”

His family has been living in a tent on the mountain for 2½ years because their village, Tal Azair, is still under Islamic State control. Two of his children died when the family’s tent caught fire, and his wife’s face and arms are scarred from burns. Her sister’s husband was killed when the militants advanced on the village.

“We don’t want these people fighting on our land,” he said. “But we have no power. It’s inevitable.”